Way to work out flow rates

[Scott_D]

Have you done your own tests or just going on the information from customer/waterboard?

 

[Last Plumber]

18lpm without. 2.2bar pressure at shower upstairs.

Customer wants more pressure as they have 25lpm at tap downstairs. 4.5bar pressure.

You need to look further into that. There's too big a difference.
If you are measuring 4.5 downstairs in a 'normal house' I would be expecting 4.0 in the loft, or there and there about's. How can it have lost 2.3 bar ?

How did you measure the upstairs pressure?

 

[Last Plumber]

Just read the original post again.

If you are measuring the Shower water pressure, (presume this is off the new cylinder)? You are measuring it after the Governor/Regulator.

If you increase the pipe size from 15 - 22 you will reduce the frictional losses. To calculate the amount you need to know route, distance, how many bends/elbows etc.

To measure the pressure loss through the supply to the cylinder you would need to know the Dynamic Pressure before the water governor on the cylinder and the same at the stop tap at the same flow rate.

I don't know if this helps?

 

[Ric2013]

25lpm and 4.4bar I believe this is static and dynamic pressure?

No. That's flow and pressure. At a guess, I'd say the 4.4Bar is the static pressure.

 

[southcoastboile]

Thanks rik. That's what I meant sorry. Just like standing and working pressure at a meter.

Thanks for reply last plumber. So let's say we know the dynamic pressure at the stopcock and before the pressure reducing valve. What calculation would you then use to work out what you would potentially gain by upgrading the pipe?
Its okay knowing pressures prior to the cylinder pressure red valve and at the stopcock but they won't be the same due to the height the water is traveling and the restrictions in the pipe work. I.e bends and sockets.
I would assume that pressure at stopcock and flow rate would be all that was needed to work out what pressure you would achieve the other end of the pipe.

For example 25lpm and 4 bar at stopcock would reduce pressure by 0.2lpm for every mtre of horizontal pipe. 0.4 every meter of vertical. 0.2 for every bend, 0.1 for every socket.

Surely someone must have come up with a simple equation like that?

 

[Last Plumber]

Thanks rik. That's what I meant sorry. Just like standing and working pressure at a meter.

Thanks for reply last plumber. So let's say we know the dynamic pressure at the stopcock and before the pressure reducing valve. What calculation would you then use to work out what you would potentially gain by upgrading the pipe?
Its okay knowing pressures prior to the cylinder pressure red valve and at the stopcock but they won't be the same due to the height the water is traveling and the restrictions in the pipe work. I.e bends and sockets.
I would assume that pressure at stopcock and flow rate would be all that was needed to work out what pressure you would achieve the other end of the pipe.

For example 25lpm and 4 bar at stopcock would reduce pressure by 0.2lpm for every mtre of horizontal pipe. 0.4 every meter of vertical. 0.2 for every bend, 0.1 for every socket.

Surely someone must have come up with a simple equation like that?

If you have 25 lpm and 4 bar at the main stop tap and you pipe the Cylinder in 22 mm tube it will sort it, yes. I think @ShaunCorbs said that earlier on in the thread.

As far as equations go, yes there are equations for water pipe sizing just like there are for just about anything you want to work with.

@steadyon posted a link to some of them.

Have you looked at those?

 

[SimonG]

What does the pressure reducing set take it down to?

 

[Last Plumber]

What does the pressure reducing set take it down to?

Must be 2.2 Bar. If he is testing the Shower?!